In general, fluid-pressurizing equipment generates various noise such as hitting sound, pressure pulsation sound, etc., caused by its pressurizing operation. To deal with this, countermeasures have been taken to allow a hydraulic damper such as an accumulator or the like to absorb pressure pulsations generated or to allow a sound insulation material to absorb the noise generated. However, since the countermeasures are of post processing, they are disadvantageous in view of space-saving and cost reduction.
To eliminate the disadvantages, a valve structure which is provided with a noise reduction function in a valve unit has been studied.
For example, first, there is known a valve structure as below. In a check valve configured to radially discharge fuel from a plurality of discharge ports formed in a valve body housing, the valve structure is provided with a buffer portion which buffers the pressure of working liquid having passed through the discharge ports. (See e.g. patent document 1.)
Secondly, there is known a valve structure in which in a check valve, a valve seat is formed in a tapered shape so that discharge-flow may smoothly move from the valve seat to a discharge port so as to have a small directional change. In addition, a conical portion sitting on the valve seat is provided on a valve body. (See e.g. patent document 2.)    Patent Document 1: JP-5-66275-U-A    Patent Document 2: JP-5-22969-U-A